Cam Timing... An excerpt from a friend
May 27, 2009, 01:35 PM
#1
Evolving Member
Thread Starter
Cam Timing... An excerpt from a friend
I think this can be of benefit to everyone who has dealt with an engine that is getting fuel, has good compression, but no spark. It happens to even engine-builders who have had numerous engine builds. Anyway, this is from a friend of mine at Wolf Motorsport in Australia.
"Hi Guys, Here's a quick email about cam timing and how important it is that the cam timing is set correctly.
Over the years we have been involved in several installation adventures, where cam timing has been found to be the culprit when an engine either would not start, or would not run correctly. If the cam timing is out a little you may still have compression, but the engine will still not run. This may lead you to think that you have everything setup correctly within the engine. Read on -
Example 1:
We had a customer many years ago with a WRX engine. They were trying to start the engine, and it would try to start and run on 2 cylinders. The workshop checked everything - trigger setup, spark and fuel. They got back to me and let me know that everything was correct, but that the engine still refused to run on 4 cylinders.
I asked, which 2 cylinders is the engine not running on. They told me that it was 2 cylinders on the left side of the motor. Now, the only common element to this engine not running on the 2 left cylinders, is the fact that they share their cams. The other 2 cylinders on the other side of the engine share another set of cams.
If all things are equal: There is spark (at the right time for each cylinder, there is fuel to each cylinder and they all have compression, then the likelihood of there being a cam timing issue on one side of the engine is quite high.
I suggested that the problem was with the cam timing on one bank of cylinders. They checked it again. They said it was right. I suggested that it was still the problem. They insisted that the cam timing was correct.
So, I went and looked at the engine myself. I checked everything again, just like they did, and everything was correct. They had fuel, and spark on all cylinders.
There was only one thing for it. I asked who it was who checked the cam timing. Each time it was checked, the same person had checked it. I asked for the owner of the workshop to check it himself. To his amazement, the cam timing on the left side of the engine was wrong.
This problem had been going on for over a week. There had been numerous phone calls to me during that time, and the workshop and their customer had been getting more and more frustrated.
Once the cam timing was fixed, the engine started and ran without further issues.
Sometimes a person will not see what is wrong in a situation, no matter how many times they look at it.
Example 2:
One of our dealers had a customer who was an expert with a particular type of 6 cylinder engine. He had rebuilt this engine the customer had. It had sidedraft throttle bodies, and should have been a good combination.
The only problem was that the engine did not idle nicely, and made less torque down low than it should have.
All regular checks were performed on the engine. It had comp, the injectors all flowed the same, the ignition system was up to scratch. It came down to cam timing. The engine builder was told that we thought the cam timing was incorrect. He believed he had the timing right, so we went back and did the tests again. Once again, we got the point where we were pretty sure the problem was in the cam or valve train area, and that the cam timing should be checked. He didn't want to check the timing as he was adamant that the timing was correct.
Our dealer (also a man who knows his stuff around engines), checked the cam timing, to find that is was not set correctly. He reset the cam timing, and as if by magic, the engine started, and ran correctly. A retune was needed, as the efficiency of the engine through its rev range had been changed. But once it was tuned, it performed as expected.
This episode took a couple of weeks from start to finish.
It didn't have to be that hard.
So, the moral of the story is to go through the basics. Work out what you think the problem could be based on what you are seeing in front of you. Don't get pushed off track by "the black box". The ECU can only be tuned to optimize the engine it is connected to. If the engine has an issue, that must be resolved before the engine will perform anywhere near its optimum.
Until Next Time,
Steve.."
It pays to have an unbiased set of eyes to QA your work or the work that was done on your car at a shop.
"Hi Guys, Here's a quick email about cam timing and how important it is that the cam timing is set correctly.
Over the years we have been involved in several installation adventures, where cam timing has been found to be the culprit when an engine either would not start, or would not run correctly. If the cam timing is out a little you may still have compression, but the engine will still not run. This may lead you to think that you have everything setup correctly within the engine. Read on -
Example 1:
We had a customer many years ago with a WRX engine. They were trying to start the engine, and it would try to start and run on 2 cylinders. The workshop checked everything - trigger setup, spark and fuel. They got back to me and let me know that everything was correct, but that the engine still refused to run on 4 cylinders.
I asked, which 2 cylinders is the engine not running on. They told me that it was 2 cylinders on the left side of the motor. Now, the only common element to this engine not running on the 2 left cylinders, is the fact that they share their cams. The other 2 cylinders on the other side of the engine share another set of cams.
If all things are equal: There is spark (at the right time for each cylinder, there is fuel to each cylinder and they all have compression, then the likelihood of there being a cam timing issue on one side of the engine is quite high.
I suggested that the problem was with the cam timing on one bank of cylinders. They checked it again. They said it was right. I suggested that it was still the problem. They insisted that the cam timing was correct.
So, I went and looked at the engine myself. I checked everything again, just like they did, and everything was correct. They had fuel, and spark on all cylinders.
There was only one thing for it. I asked who it was who checked the cam timing. Each time it was checked, the same person had checked it. I asked for the owner of the workshop to check it himself. To his amazement, the cam timing on the left side of the engine was wrong.
This problem had been going on for over a week. There had been numerous phone calls to me during that time, and the workshop and their customer had been getting more and more frustrated.
Once the cam timing was fixed, the engine started and ran without further issues.
Sometimes a person will not see what is wrong in a situation, no matter how many times they look at it.
Example 2:
One of our dealers had a customer who was an expert with a particular type of 6 cylinder engine. He had rebuilt this engine the customer had. It had sidedraft throttle bodies, and should have been a good combination.
The only problem was that the engine did not idle nicely, and made less torque down low than it should have.
All regular checks were performed on the engine. It had comp, the injectors all flowed the same, the ignition system was up to scratch. It came down to cam timing. The engine builder was told that we thought the cam timing was incorrect. He believed he had the timing right, so we went back and did the tests again. Once again, we got the point where we were pretty sure the problem was in the cam or valve train area, and that the cam timing should be checked. He didn't want to check the timing as he was adamant that the timing was correct.
Our dealer (also a man who knows his stuff around engines), checked the cam timing, to find that is was not set correctly. He reset the cam timing, and as if by magic, the engine started, and ran correctly. A retune was needed, as the efficiency of the engine through its rev range had been changed. But once it was tuned, it performed as expected.
This episode took a couple of weeks from start to finish.
It didn't have to be that hard.
So, the moral of the story is to go through the basics. Work out what you think the problem could be based on what you are seeing in front of you. Don't get pushed off track by "the black box". The ECU can only be tuned to optimize the engine it is connected to. If the engine has an issue, that must be resolved before the engine will perform anywhere near its optimum.
Until Next Time,
Steve.."
It pays to have an unbiased set of eyes to QA your work or the work that was done on your car at a shop.
